We found this mark as described, set in the south face of a gray-painted, curved concrete wall partially surrounding the southeast corner (Hudson & Clarkson Streets) of the James J. Walker ballfield. The benchmark was hard to spot beneath the thick layer of gray paint. The paint also makes the stamping difficult to distinguish, but with some effort it can still be read.

[i]A report on the condition of this mark has been submitted to NGS, along with the following recovery note:[/i]

Recovered in good condition. Concrete wall and disk have been painted over but designation is still legible. Autonomous (non-corrected) handheld GPS coordinates for the station are 40 43 46.43(N) 074 00 23.96(W).

Note, however, that the city painted the disc the same color as the concrete wall. It is easy to miss this one! I walked past it twice before I found it.

[last edit: 9/26/2003 11:30:08 AM PST]

Documented History (by the NGS)

1/1/1974 by NGS (MONUMENTED)

DESCRIBED BY NATIONAL GEODETIC SURVEY 1974
AT NEW YORK. AT NEW YORK, IN THE BOROUGH OF MANHATTEN, AT THE INTERSECTION OF HUDSON AND CLARKSON STREETS, SET VERTICALLY IN THE SOUTH FACE OF CONCRETE WALL AT THE SOUTH EDGE OF THE PLAY AREA, 30.3 FEET EAST OF THE EAST CURB OF HUDSON STREET, 14.1 FEET NORTH OF THE NORTH CURB OF CLARKSON STREET AND 3.3 FEET ABOVE THE SIDEWALK.

Control Text

The horizontal coordinates were scaled from a topographic map and have an estimated accuracy of +/- 6 seconds.

The orthometric height was determined by differential leveling and adjusted by the National Geodetic Survey in June 1991.

The geoid height was determined by GEOID99.

The dynamic height is computed by dividing the NAVD 88 geopotential number by the normal gravity value computed on the Geodetic Reference System of 1980 (GRS 80) ellipsoid at 45 degrees latitude (g = 980.6199 gals.).